OCaml on Windows

This installer is out of date

This installer no longer works. Do not use it. Here's some suggestions:

Andreas
Hauptmann's installer is very solid and does a great job of
doing what this installer once did. It also gives you a working OPAM,
thanks to Andreas' excellent work in patching every single package in
existence to work on Windows.
What you're getting is a custom (old) OPAM that was patched by Andreas, his diff is
at https://bitbucket.org/fdopen/opam.

Introduction

There are
several ways to compile and distribute OCaml on Windows.
This installer distributes the native, mingw-w64, 64-bit port of
OCaml along with a native, 64-bit OPAM. The installer offers to
install Cygwin so that you get 1) the proper compiler toolchain needed
to use ocamlopt and 2) Unix tools such as make,
bash and others, which most packages depend on.

Andreas' repository contains patched packages (so that more of
them build on Windows); it also contains depext-cygwinports,
an OPAM plugin that is capable of fetching system dependencies as
cygwin packages for the x86_64-mingw64 toolchain. Concrete example:
opam depext ssl will call into Cygwinports to make sure that
openssl gets installed into your Cygwin setup for the right toolchain.

Known issues

Most antivirus software will flag the OCaml installer as being a
virus, because OCaml is using NSIS (see the NSIS
website). There is a discussion in issue
17 on the bugtracker; the last
comment provides indications for reporting the installer as a false
positive. Please do.